Rework CLI to work like git or svn CLI
Add timestamp to log output, set default log level to INFO
New command: install-iso. Simplify build_ami_from_rootfs.
Get the absolute path of the .iso file
Do not try to build the ami if extracting the iso failed
Unbreak build_ami
Remove mnt dir and work dir options

The script uses temporary dirs for them now
Log output of check_cmd() command while it is running

Should prevent buildbot from aborting the build because `make` runs for
too long without outputing anything
Make sure we are compatible with the old toolset for now
Add doc for omi-factory
Merge branch 'wip/cli-ng'